The proposed studies aim to characterize the memory impairments produced by damage to the medial temporal lobes by examining recognition memory in amnesic patients suffering from cardiac arrest and stroke. Recent research has revealed that although these patients exhibit debilitating memory impairments for a broad range of materials, recognition memory for some types of information can remain well preserved. These results challenge our current theories of memory and the medial temporal lobes, and indicate that the memory impairments seen in amnesia are not as general as previously thought. The current proposal aims to determine the factors that are responsible for the impaired and unimpaired memory abilities of these patients by examining their memory deficits in tests of item recognition for a wide variety of stimuli (e.g., faces, scenes, complex visual and auditory stimuli), as well as across a range of different types of associations (e.g., pairings of visual and auditory materials, objects and scenes etc). The studies will be first to examine the effects of several critical factors that have not been previously studied in amnesia. Moreover, the proposed studies make use of sophisticated measurement methods such as receiver operating characteristic analysis that will provide precise quantification of the memory abilities of these patients, not possible with previous methods. Finally, the studies will provide a unique opportunity to directly test novel theoretical perspectives, and thus promises to lead to significant advances in our understanding of normal and abnormal memory functions in the human brain.